Moving along I find that I have been encountering odd areas bounded by straight lines beyond which is only blackness on the minimap and dead air on the screen... movement is impossible except to go back. Like a black impenetrable curtain. These areas are geometric, always bounded by straight lines, sometimes at 90 degrees... if I get out and reboot and return they gradually fill in with details but oddly I first see any underground features... all the caves etc... and then the ground, trees etc. Kind of curious if it has to do with memory issues, maybe I have too many goodies turned on or something. But still...straight lined borders are quite common... long, long miles of jungles ending in a sharp line of transition to a desert, for instance. Any idea why the borders are not more natural or fractal? Are the two things related? I'm nowhere near any edge of the Universe and often these dead zones cover area I had previously entered and built up.MT 0.4.16 and Kubuntu 17.04 on an Asus laptop....